Abstract—Considering the nonlinear characteristic of
components in vehicle is very important in designing the
controller of automobile active suspension system. To show the
importance of this effect, a nonlinear optimal control method
is employed in this paper. At first, an optimal law is developed
for active suspension by the states prediction of a nonlinear
quarter car model. The states of quarter car model are first
predicted by Taylor series expansion and then a control law is
introduced by minimizing the local differences between the
predicted and desired states. In this way, the well defined sky
hook linear model is selected as the reference model to be
tracked by the nonlinear optimal controller. In order to
decrease the vertical accelerations and improve the behavior
of the reference model, the sky hook model is controlled
beforehand by the LQR method. Derived control law has an
analytical form which is easy to apply. The simulations show
that under the proposed controller, the car has well passenger
comfort and safe maneuverability.